The invention relates to a stabilized organophosphorous composition and a process for the preparation thereof.
Organophosphites and polyorganophosphites have been used for a variety of applications including preservatives (e.g., antioxidants) for plastic materials and as ligands for catalysts. However, maintaining the stability of phosphite ligands can be problematic. To be effective, the ligand and related catalyst must be stable under reaction conditions. The stability of the ligand can be negatively impacted by impurities, especially those that accumulate in the ligand during storage.
U.S. Pat. Nos. 3,283,037 and 3,437,720 discuss the stability of phosphites in air and at elevated temperature. U.S. Pat. No. 4,835,299 teaches how to remove impurities from organophosphites, but not how to prevent formation of the impurities.
WO 2013/066712 discusses the problem of residual solvent in polyorganophosphites and the impact of residual solvent on storage stability. In particular, residual solvent can contribute to ligand oxidation and/or hydrolysis. Similarly, WO 2013/098370 teaches that some solvates may result in clumping upon long term storage. US 2013/0225849 discloses the use of trace amounts of sodium methoxide as an additive in a washing step during the purification phase of the ligand manufacturing process to address the instability of polyorganophosphites in the presence of residual solvent. However, the presence of such an extremely strong base is not suitable in many catalytic processes, such as hydroformylation, hydrocyanation or hydrogenation. US 2013/0225849 also teaches that the strong base is removed prior to packaging. Thus, US 2013/0225849 teaches how to remove impurities from organophosphates, but not how to prevent formation of the impurities.
There is a need for a means to enhance the storage stability of hydrolyzable organophosphorus compounds that would not require compounds that are highly alkaline or otherwise not tolerated by downstream applications such as hydroformylation, hydrocyanation or hydrogenation.